Question 144, As shown in the figure, plane plane , is an isosceles right triangle, , quadrilateral is a right trapezoid, , points and are the midpoints of and respectively. Find the sine value of the angle formed by line and plane .
Problem 804
Official solution
Question 144, Solution: As shown in the figure, according to the conditions, we can supplement the figure to form a cube EFGH with a side length of 4. Taking the midpoint of as , then is parallel and equal to , so quadrilateral is a rectangle. Taking the midpoint of as , then .
Since , and the distance from to the plane is 4, thus . Also, , so according to Heron's formula, . Therefore, we have
Noting that , the sine value of the angle formed by the line and the plane is .